1. Field of the Invention
The present invention relates to novel compounds. More particularly it is concerned with alkyl cyclam which can be used in selectively and efficiently capturing metal ions, for example, metal ions contained in waste water.
2. Description of the Prior Art
Metal ions such as copper, cobalt, nickel, mercury, cadmium, zinc and the like ions contained in waste water have hitherto been removed from the standpoint of preventing pollution. Metal ion capturing agents for use in removing these metal ions include activated carbon, kieselguhr, and the like, which capture the metal ions by the physical absorption action, and ion exchange resins, chelate resins, and the like, which capture the metal ions by the chemical binding action. These metal ions capturing agents, however, are of no practical value since activated carbon, kieselguhr, and the like are insufficient in removing low concentrations of the metal ions, and ion exchange resins are of low selectivity to the metal ions. With regard to chelate resins, since they are of high selectivity to all the heavy metal ions, they are suitable for use in removing all the heavy metal ions from industrial waste water for preventing pollution. These chelate resins, however, have a disadvantage in that since they are of low selectivity to specific metal ions, they cannot be employed in selectively separating, purifying and concentrating a specific metal ion from the metal ion mixture in which various kinds of metal ions coexist, for example, in recovery of noble metal and the like.
As a method of separating or concentrating uranium from an aqueous solution containing uranium, a solvent extraction method using amines is known. This procedure, however, is markedly disadvantageous from a practical standpoint since it requires a large amount of amines because of its low ability to form a complex with uranium.
Thus it has long been desired to develop novel materials capable of selectively and effectively capturing metal ions. We have found that cyclam (i.e. 1,4,8,11-tetraazacyclotetradecane) forms a stable complex compound with copper ion in an aqueous solution. Further, we found that a novel compound resulting from the substitution of one or more hydrogens of the cyclam by alkyl groups has an excellent ability to capture metal ions selectively.